Removal of H2S has become increasingly important because of the increased need for natural gas production. Approximately one-third of U.S. natural gas resources can be considered as low or sub-quality gas not suited for pipeline shipment with impurity concentrations in natural gas varying from traces to 90% by volume. In natural gas processing H2S is viewed as a pollutant because it corrodes pipelines and deactivates metal-based catalysts used in steam methane reformation (SMR). There are a number of known H2S removal processes practiced commercially or in bench scale demonstrations. Based on the H2S reactions involved, these technologies can generally be separated into three categories:Decomposition: H2S=½S2+H2ΔH°298K=79.9 kJ/molReformation: 2H2S+CH4=CS2+4H2ΔH°298K=232.4 kJ/molPartial oxidation: H2S+½O2=S+H2OΔH°298K=−265.2 kJ/mol
Unfortunately, commercial systems based on any of the H2S removal processes shown above generally include one or more significant shortcomings, such as low efficiency and several technical issues, such as chelate loss, solution loss, slow oxidation rate. In addition, the scrubbers are generally complex designs that involve high capital and operation costs. What is needed is a new H2S removal process and related system that provides improved efficiency, and a relatively low capital cost system that also provides reliable and relatively low cost operation.